feat(you-retriever): Support You.com News API

[christeefy]

You.com has both a Search and News API. Currently the YouRetriever only supports Search.

This PR enables it to also support News, while maintaining backwards compatibility.

This update has been manually tested:

from dspy.retrieve.you_rm import YouRM

search_rm = YouRM(endpoint="search")
res = search_rm("Who is the most famous singer in the 90s?")

news_rm = YouRM(endpoint="news")
res = news_rm("Latest pop songs")

[arnavsinghvi11]

Thanks @christeefy !

It would also be great if you could add documentation for the YouRM to provide context as done for the RMs. Feel free to add all relevant content for the YouRM API documentation linked).

[christeefy]

@arnavsinghvi11 done, PTAL! 😊

[arnavsinghvi11]

Thanks @christeefy !